Method of and apparatus for producing x-rays



C. D. EHRET.

METHOD'OF AND APPARATUS FOR PRO'DUCING X-RAYS.

APPLICATION FILED Nav= I3, 191s..

FIG. r1

IIIIIIIIIIIIIIIIIIIII'III'l'I l v Ffcl f--IIIIIIIIIIIIIIf ffjQ L`- I|I-IIIIIIIIIIIIIIIIIIIIIIIIIhL Bjv IINVENTOR i la citizen ofthe United States, residin in of Pennsylvania,

UmTED STATES rATENrorricE.

CORNELIUS D. maar, or HILADELPHIA, rENNsYLvA'NIA.

METHD OF-.AND APPARATUS FOR PRODUCING' X-RAYS.

To all w-wm z't may concern.'

Be it known that I, CORNELIUS D. EHRET,

the city and county of Philadelphia, tate ducing X-Rays, of which the following is a specification..

My "nvention resides in an X-ray tube comprising an anti-cathode or target spaced in vacuo from a cathode which remits electrons or emits secondary electrons as a result of bombardment by primary electrons emite` ted by a body which -does` not directly cooperate with the target or anti-cathode and which may be disposed outside of the chamber containing the target, as in an evacuated tube-or bulb\ attached to the principal bulb.

My invention resides also in the method of producing X-rays hereinafter described. For an illustration of some of the various forms my inventionmay takepreference -is to be had to the accompanying drawing, in

which:

' Figure 1 is a side elevation, partly in section of an X-ray tube embodying my invention.

f Fig. 2 is a side elevation, partly in section,

take. Referring to Fig. 1, T is an of glass or. other suitable material having therein the anti-cathode or Starget A whose face as usualI is of tungsten or other suitable refractory material. Spaced from the targetA is the cathode C, of platinum or other suitable material, vof any suitable form,

here shown of usual cup form, sealed around its edgeorperiphery to the inner end of the 'hollow glass stem S attached to the main tube orbulbT and completely closed or sealedgto form a chamber D separate from the main bulb Cathode C` seals the two chambers' from each other-and forms a wall common to them.

The chamber D ishighly eXhausted,-and preferably to such degree that susbtantially pure electron; dischargemakes place therein,

though the presence o -gas or ionizable ma-v terial lis also `within my invention. The primary example illustrated, a tun suitable filament brou ht to suitably high temperature or ,incan escence by current from thesource b 'and adjusted as to strength by the variable resistance r.

-From cathode C-there extends tothe er;-

have invented a new andfor production of X-rays. 'useful Method of and Apparatus for Proray tube' electron emitting body F is, in the gsten or other Speciivcation of LettersfPatent. Patented Apr. 20, 1920- Applieation filed November 131918. Serial No. 262,277.

terior a conductor, asc, which, as illustrated may be sealed or inclosed within a wall oi stem S. n g

In the main bulb T is a vacuum suitable It may be so high as to permit passage of current only by substantially pure electron discharge; or

character and of suitable voltage, has its' one terminal connected by conductor c to cathode C and its other terminal to the electron emitting body F. When body F is negative with respect to'cathode Cthe electrons emitted by body F strike at high velocity on the side of cathode C facing body F as a result cathode C remits electrons or emits secondary electrons in far greater 'quantity than emitted bybody I1F. The

source of current B1, of any suitable character and of suitable voltage, as from 30,000 to 150,000 or more volts, depending on char- -acter of results required and the degree and character of vacuuni in tube T, is connected t0 cathode C andto anti-cathode A. When the anti-'cathode is positive with respect to cathode C, the greater quantity of electrons emitted by cathode C strike target A at extremely high velocity and produce X-rays of great intensity or quantity.

When the vaguum in chamber D is so high that substantially pure electron dischargeL occurs therein, filament F will have tive ions, while at the same time in the main bulb gas or ionizablegmaterial may be employed at lesser degree of vacuum than in chamber D. e

In Figl2, the Vprimary electron emitting body F "is disposed in the bulb or tube T in which the vacuum may be of any of the de- 1 a long life because not bombarded by posi- Y grees or characters referred to in connection with Fig. 1. lIt is again shown as a L10 filament whose temperature is controlled by variableresistance'r, It is housed Within o common'tosaid chambers,

` ,which consists inbom l A'said cathode, an

ence ofdpotential between said anti-'cathode namedbombardment.

Y terial, intervening between body F and anode A and open at its end toward cathode Herev again cathode C is bombarded by electrons fromfbody F and remits electrons in larger extremel at claim is:

1. The method of reducing X rays', which consists in excitmg abody tojemit primary electrons, bombarding acathode by said` -primary electrons to cause re'e'mssion of secondary electrons, l l anti-cathode to produce X-rays bysecondand bombarding an aiyelectrons remitted by 'said cathode to -thefexclusion of bombardment by said 'pri mary' electrons.

2. The method of reducing `X rays, arding through a vacuum a cathode by electrons to cause re- 'emission from said cathode into another i vacuum,

and bombarding an anti-cathode by electrons duce X-rays.

3. Apparatus for Producing X-rays comprising'a source' o electrons, a cathode, means producing a difference of, otential between said source and said catho e where/- electrons om' said source and caused to remit electrons, an' anti-cathode disposed in a vacuum with saidcathode and subjected to bombardment electrons remittedfrom only lb means producing a'diferand'sai cathode for effecting said second A11 X-ray tube comprising an evacuated vessel,"an imperforate cathode and an anticathode.tlferein, a heated cathode discharge between'which and said anti-cathode v `is prevented maintaining by said cathode, and means for said ca hode atl a potential higher than said heated cathode and lower than said anti-cathode', whereby said cathode "isbombarded by emissions from said heated cathode'and said anti-cathode is bombarded 'by'remissions from said cathode.

.5. An X-ray tube comprising` evacuated chambers, a cathode`form1ng a sealing Wall Y said chambers emitting electrons bombardci-ilantity which striketarget A atv 'gh velocity and produce X-rays.-

charge, and a bod remitted by said cathode to pro-V u'ated chamber,

' within said' chamber,

a body in one of manage other of said chambers bombarded by electrons remitted b said cathode. 6. An X-ray tu comprising amain 'evac- `uated bulb, an anti-cathode thereln, an evacuated .stem on said bulb, a.=cathode forming a sealing wall between said main bulb and said stem, and a'body'in said stem emitting. .electrons bombarding said cathode. f

An. X-rayftube comprising a bulb, a cathode and an anti-'cathode therein, a separatechamber evacuated .to a' degree suit-v able for substantially `pure electron dis'- in said chamber emitting electrons-bomba g said cathode, evacuated to lesser de ee than said chamber and containing ionlzable material,l said cathode forming a Wall common tosaid chamber and said bulb. 8. An X uated chamber, an anticathode therein, a co'- operatin cathode forming a sealing wall of lsaid c' amber, and means external to said chamberl for causing said cathode `to emit electrons into said chamber.

9.An X-ray 'uated chamber, a cathode, a cooperating anti-cathode in said chamber, an electronf emittingbody forexciting-'said cathode by bombardment to cause remission of lelec- -ray tube comprising an evacsaid bulb-r l..

tube comprising an evacv trons, and means limiting the bombardment trons'bombarding said cathode to 'cause rey emission of electrons, and structure relating said cathode with respect to said body vand said anti-cathode to prevent direct emission fromsaid body to said anti-cathode. t

11.*An X-ray tube comprising an evacan fanti-cathode therein, a cathode having an and electron-emitting means within a space completely isolated from said chamber-'infor bombarding said cathode' to cause 're'mission from` its said emitting face `to said anti-cathode.

In testimony whereof I- haveighereunto" aiixed-mysignature this 12th dany "bfjNovember, 1918.- J

v 1 GORNELiUs D. EHR-ET.

in said chamber, a stem on said' electron-emitting face 

